This research will identify and then remediate adolescent decisional and social skills related to sexual behaviors which place them at risk for sexually transmitted diseases (STDs), including HIV infection. Phase I will involve two samples of sexually active adolescents and two samples of professionals who work with sexually active adolescents. Phase I will develop set of socially valid assessment procedures to pinpoint specific situations, decisional processes, and social skills, associated with high-risk sexual behavior. Phase 2 will use these procedures to identify individually relevant decisional and social skills and provide a brief prescriptive intervention to help adolescents avoid high-risk sexual behaviors. This intervention will be conducted and evaluated in STD clinics with adolescents who have previously had at least one STD. The entire project will be guided by recent theoretical models of social competence emphasizing the importance of both cognitive and behavioral skills, and will use assessment approaches and intervention procedures found to be effective with other adolescent problem behaviors.